Welding gun



Feb. 8, 1944. l w, A. WEJGHTMAN WELDING GUN Original Filed Aug. 25, 1939-654 i @50' 6 Zm [NVE/VT@ W'LllinmAM/elghkman.

Patented Feb. 8,-1944 WELDING GUN William A. Weightman, Philadelphia,Pa., assignor to Edward G. Budd Manufacturing Com, pany, Philadelphia,Pa., a corporation of Pennsylvania Original application August 25, 1939,Serial No. 291,838. Divided and this application August 27, 1941, SerialNo. 408,418

16 Claims.

This invention relates to a welding gun and has for an object to providean improved convenient and compact device of this class which may bequickly removed for servicing.

Another object of the invention is to provide an apparatus of the typedescribed employing air pressure to establish the welding electrodepressures and in which the felding electrode pressure may be of theorder of 1600 pounds.

Still another object of the invention is to pro- Vied an apparatuscapable of forming a plurality of spot welds closely spaced on a curvedmember where the -axis of the spot welds is normal to the curvature. Y

A still further object of the invention is to provide in such anapparatus a double-acting floating welding gun capable of effectingcontact with the work with uniform pressure on each side and separatingfrom the work after the weld is completed all inthe fraction of a secondThe above and other novel features of the invention will appear morefully hereinafter from the following detailed description when taken inconnection with the accompanying drawing. It

is expressely understood, however, that the drawing is einployed forpurposes of illustration only and is not designed as a definition of thelimits of the invention, reference being had for this purpose to theappended claims.

Figure 1 is a front and side perspective View of an individual slidingor oating welding gun.

Figure 2 is a rear and side perspective view of a welding gun.

Figure 3 is a longitudinal section through a welding gun, a structure tobe welded and part of another opposite welding gun being indicated bydotted lines.

Figure 4 is a section taken on the line 24-24 Each welding gun issupported upon a bracket,

600 secured by bolts 602 and 604 upon a table or block 426 of amachinestructure such as disclosed in applicants aforesaid parent application.'11e bracket is provided with a perpendicularly extending slide supportor -head 608 upon which is slidably supported a. cylinder 6H), thecylinder having integrally arranged therewith a complemental recess 612adapted to slidably engage the support head. The cylinder at the headend thereof carries a welding electrode carrying block; 6I4 havingsecured on one end thereof a. welding electrode tip adaptor 6I6 having awelding electrode 6I8 threaded therein The other end of the block 6l4 isprovided with one end of a flexible connector such as 504 or 206 as thecase may be. The welding electrode adaptor 6l6 is preferably providedwith-a central rib 620 arranged in a groove 622 (Figure A1) in theelectrode block 6I4 and is held in place by the screw 624 having arecess in the top thereof to receive a suitable wrench. The groove 622in which projection,

620 extends may be set at any` angle in order to locate the electrodetip in a proper position and the adaptor may be slid to any desiredposition in the groove and thereafter tightened in place to likewiseposition the electrode. The electrode carrying block 614 is insulatedfrom the cylinder by a layer of insulation 626 and insulation 628surrounding a stud 630 (Figure 3) by which the 'block is secured to thecylinder head.

The cylinder is provided with a piston 632 having a hollow piston rod634, the same extending outwardly through the bottom of the cylinderthrough a stumng box 636. The lower end of the piston rod 634 isprovided with a shank 638 and a threaded extremity 640 on which arepositioned two halves of the lower end of a yoke 642 (Figs. 1, 2 and 4).The yoke comprises a pair of parallel straps 644 extending vertically inguide ways 646 arranged integrally with the cylinder structure and thesestraps are bolted together at the top around an upper electrode block648, the same, however, being separated electrically from the electrodeblock through insulation 650, 652 and insulation sleeves 654 upon thebolts 656. The lower ends 658 of the yoke members 642 are securedtogether around the shank 638 of the piston rod by engaging a taperedlower portion 660 of the lower ends of the yokes with a tapered shell662 adaptedto be forced upward by the nut 664 upon the threaded end 640of the shank 638, the lower ends of the yokes thereby being urgedupwardly into engagement with the shoulder 666 formed by the end of themain portion of the piston rod and the shank 638. The upper electrodeblock 648 is provided with an electrode adaptor 6l6 having an electrodetip 6I8 therein and the electrode adaptor is secured to the block by abolt and nut 668, the block having after continued pressure on the topside of the piston and urging against the upper end of the cylinderforces the cylinder to raise itself sliding upon the support guide head608 thereby bringing the lower electrode HI8 into engagement with thecap strip 30. Since the pressure employed l is sufficient to establish awelding pressure between the electrodes, it will be seen that, exceptfor`the weight of the parts, the pressure on the upper electrode tip andthe lower electrode tip is completely equalized by the sliding movementpermitted between the'upper electrode and its yoke and the cylinder andits slidable support. To prevent flash or molten metal from clogging themovement of the various slide members, the upper electrode block isprovided with a shield 614 which cooperates with the lower electrodewhen the electrodes are in engagement so as to block the path of anymetal exploded away from the workpiece toward the guide 646 and the yoke642.

To separate the electrodes fluid pressure is admitted to the undersideof the piston through the port 616 in the lower end of the cylinderthereby permitting the cylinder to lower away from the work piece untilthe lower welding block 6|4 strikes the guide head 608 at the point 618and thereafter lthe piston is raised within the cylinder to a furtherextent to elevate the yoke and upper electrode tip 6l8 to the disengagedposition. Because of the iioating movement of both the cylinder andpiston the air pressure connections are made thereto through flexiblehoses 680 and 682 which flexible hoses are detachably secured to ports684 and 6 86 extending through the support bracket 600. The upperelectrode block 648 is suitably water cooled by a bore 688leading'thereinto and a concentric tube 690 leading substantially to thebottom of the bore, water being circulated through the tube 690 into thebore and thence -out through the outlet 692. The lower electrode blockis cooled by a copper water-carrying tube 694 lying in a U-shaped groove696 extending around the edge and the underside of the electrode block614.

By reason of the construction described it will readily appear that uponthe disablement of any gun, the same may be quickly substituted byanother gun without great loss of time by simply sliding the cylinderand piston and its yoke from the supporting bracket 608 afterdisconnection of the electrical connections, air connections and watercooling connections. Likewise electrode tips may be quickly replaced bymerely unscrewing the tip from its adaptor and if difculty results fromremoving the tip from the adaptor, the adaptor may be removed from itsblock by loosening its associated threaded fastening means, it beingunderstood that the adaptor engages the threaded fastening means with aU-slot SI1.

It will be understood that the electrode supporting blocks areconstructed of a metal high in electrical conductivity as well asstrength and that the electrode tips themselves may be made of a specialalloy such as Mallory metal.

yokes in order to supply sufficient strength are preferably made ofstainless steel and the parts in general around the gun are of suchmaterials as would be non-magnetic and unaifected by the heavy currentsandv magnetic iields produced thereby.

When iiuid pressure is admitted to one side of the piston, the mechanismfor controlling such pressure automatically provides for releasing thepressure from the oppositeiside of the piston. Due to the guns beinglonger below the work, than above, the center of gravity of each gun isbelow the work and they may be placed closer together on work that islongitudinally curved downward than on upwardly curved work.

This invention relates principally to apparatus having spot weldingelectrodes of the oating type, that is, in which each electrode isadapted 'to be movable so that where a number of pairs of separateelectrodes are used, as in spot welding, the pressure transmitted to thework by each pair of electrodes will be uniform with the pressuretransmitted by each other pair of electrodes to obtain uniformity in thework irrespective of whether the work be of precisely uniform thicknessand whether the electrodes are each of exactly the same length.

Each welding gun contains a fluid pressure device, and is compact sincethe pressure piston and cylinder are arranged vertically within the Agunfor direct cooperation with the welding electrodes to avoid anydiminution in the power transmitted to the electrodes by the iiuidpressure piston and cylinder. The ease of removing any gun upon removalof the electrical and huid pressure connections aids the rapid operationand servicing of this device.

The gun is removable from its upstanding supporting guide 608 by slidingit upwardly after removal of the electrical and uid connections. Above61B this upstanding guide should be substantially longer than themaximum separation of the Welding electrodes in order that the gunl maynot be removed from this upstanding guide in event the work should belocated close to the upper electrode where the electrodes are spacedapart a maximum amount. As the electrodes close, the `weight of the gunis transferred from the abutment 618 to the work and the upper electrodeas soon as the lower electrode begins to move toward the work afterimpingement of the upper electrode upon the work'.

I claim:

1. A welding gun having opposite electrodes. vparallel guides alongwhich each electrode is slidable, and means for moving each electrodetoward and from and with respect to the work, one of said guidesconstituting a support for said gun and along which the gun is moved asa unit on insertion of the gun in operative position and on removal ofthe gun from such position, cooperating means on said support and saidgun for supporting the latter in a rest position when the electrodes areout of engagement with the work.

2. A welding gun having an upstanding guide along which the gun isslidable for movement to and from its operative Iposition, a pair ofopposite electrodes each of which is movable with respect to the Work,support means on said guide for supporting said gun when the electrodesare out of contact with the work, means for moving the upper electrodecontiguous the work, and means for raising the lower electrode andsimultaneously changing the weight of said gun from said The supportmeans to the work, whereby the work assists in the support of the gunduring welding, each of said means being constructed to apply uniformpressures on the electrodes except for the weight of the gun.

3. A spot welding gun having an upstanding guide along which the gun isslidable for movement to and from its operative position, a pair ofopposite electrodes each of which is movable with respect to the work,support means on said guide for supporting saidgun when the electrodesare out of contactwith the work, a piston and cylinder each supportingan electrode, one of said piston and cylinder being slidable along saidguide above said support means for moving its elec- Y gun to insurefreedom of oating to its opposite electrodes when the center of gravityof said gun is below the work which comprises, supporting the gunindependently of the work, lowering its upper electrode into contactwith the work, and then transferring the weight of the gun from itssupport to said upper electrode and work simultaneously with raising thelower electrode into contact with the work, and uniformly pressing bothelectrodes against the work during welding except for the weight of thegun being on the upper electrode.

5. In a welding gun having a pair of electrodes adapted to move towardand away from one another under pressure, a bracket for'one of saidelectrodes, guideways in the opposite sides of said bracket, a splityoke, having a portion slidable in each guideway and carrying said otherelectrode at the loop end thereof, a cylinder in said bracket, a pistonin the cylinder, having a piston rod extending through the end of thecylinder and means for clamping the split ends of said yoke around theend of said piston rod whereby to move said electrodes into and out ofengagement with the work.

6. In a welding gun, a holder for one electrode of a pair of coactingelectrodes, a connecting member attached to said holder at one end andinsulated therefrom, a support for the other electrode of said pair ofelectrodes, at least one guideway in the side of said support forslidably receiving said connecting member, motor means secured to saidsupport and to the other end of said connecting member to reciprocatesaid member relative to said electrode support.

7. In a welding gun, a holder for one electrode of a pair of coactingelectrodes, a connecting member .attached to said holder at one end andinsulated therefrom, a support for the other electrode of said pair ofelectrodes; at least one guideway in the side of said support forslidably receiving said connecting member, motor means secured to saidsupport and to the other end of said connecting member to reciprocatesaid member relative to said electrode support and means to slidablymount said support for movement substantially parallel to said guideway.

8. A welding gun having opposite electrodes. a

guide on which the gun is mounted and along which it isslidable forremoval, a fluid pressure cylinder at one side of said guide, a pistonand piston rod in said cylinder, guides arranged one on each side ofsaid cylinder, yoke members slidable in said guides and connectedtogether adjacent each end of said cylinder, means adjacent one end ofsaid cylinder for connecting said yoke members to said piston rod, anelectrode secured I to said piston rod, the opposite electrode beingcarried by said yoke members with the cylinder secured electrode betweenthe opposite electrode and said cylinder and piston.

9. A welding gun having opposite electrodes, an upstanding guide onwhich the gun is mounted and along which it is slidable as the lowerelectrode is moved into cooperation with the work, a iiuid pressuretranslating device for moving each electrode toward the work, said loweryelectrode being xed with respect to one portion of said device and theupper electrode being fixed with respect to another portion of thedevice that is relatively removable with respect to the first portion,another guide parallel to the i'lrst mentioned guide and along which theupper electrode is movable, said gun being removable by sliding the sameup the first guide, an abutment on the first guide for supporting saidgun when not welding, said uid pressure device being constructed tolower the upper electrode into contact with the work by movement alongsaid second guide and then move the lower electrode into contact withthe work after the said gun and device are raised along the first guide,the work carrying the gun during welding, and the rst guide being longerthan the maximum separation of 'said electrodes whereby the gun isprevented from sliding off said first guide in event the work werelocated close to the upper electrode when said electrodes are widelyseparated.

10. In a welding device, a pair of coacting electrodes, supports forsaid electrodes, guiding means having complementary parts with slidingsurfaces for at least one of said electrodes adapted to allow relativemovement between said electrodes toward and away from eachv other, saidguiding means extending close to and along the gap between the tips ofsaid electrodes, the part of said guiding means which is connected toone of said electrode supports extending at least partly along theaforesaid space on the outside of the complementary part of said guidingmeans so as to protect the sliding surfaces of the guiding means againstsplash during welding.

11. A welding gun having opposite electrodes and supports therefor, apair of spaced guides, a member slidable along said spaced guides andsecured to one electrode support, another guide intermediate the spacedpair and along which the other electrode support is slidable, and fluidpressure means for sliding each electrode support along its guideway.

12. A welding gun having opposite electrodes, a fixed support forthegun, means for moving one electrode into cooperation with the work,means' 13. A spot welding gun having opposite electrodes each movabletoward and from work to be welded, a guide, a pressure-exerting deviceformed of twov relatively movable inner and outer parts, the outer parthaving closed and open ends, with the inner part extending into theouter part through the open end thereof, and one of said electrodeshaving attachment to the closed end of the outer part, slide Ways on theouter surface of said outer part, and sliders movable in said slide waysand connecting said inner part, at the open outer part end with theother of said electrodes.

14. A noating welding gun comprising a support, a weldingelectrodeslidably mounted upon said support for movement-generally in thedirection of the axis of the electrode, a second welding electrodeslidably mounted with respect to said support for similar movement andmeans for moving said electrodes with substantially equal force intoengagement with a work piece, said means including a cylinder havingouter axially aligned side slide ways, and a piston, one end of saidcylinder being closed and one of said electrodes being mounted upon saidcylinder near the closed end thereof, the other one of said electrodesbeing connected to said piston by a structure extending through theother open end of said cylinder and along the outside thereof.

15. A welding gun comprising a support. a guide mounted on said support,a device movably supported in said guide, said device having two Dartseach freely and unopposedly movable relatively to the other, anelectrode secured to each part of said device in cooperativerelationship with each other, and pressure means for forcing said deviceparts towards and from each other in a time sequence. A

16. A welding gun having a normally vertical position of operationcomprising a support, an approximately vertical guide mounted on saidsupport, a device mounted for up and down movement in said guide, saiddevice having two parts and'an electrode secured to each part o! saiddevice in cooperating relationship with each other, and pressure meansfor positively forcing said device parts toward and from each other inAa time sequence.

WILLIAM A. WEIGHI'MAN.

